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Home >> Audi >> 2009 >> A4 Base, 2D Convertible >> Repair and Diagnosis >> External Pages >> Different car >> Section 1247 (EPAS Guided Routine Testing) >> Pinpoint Tests >> Pinpoint Test AP: PSCM DTC U0159 Lost Communication With The PAM >> PSCM Circuit Information
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PSCM Circuit Information

WARNING: This page is about a different car, the 2018 Lincoln Navigator. However, it is still accessible from the selected car via links, so may be relevant.

Refer to POWER STEERING CONTROLS , for schematic and connector information.

Refer to Steering GSB for additional connector and wiring inspection tips.

CAUTION: Use the correct probe adapters when making measurements. Failure to use the correct probe adapters may cause damage to the connector.
Fig 1: Data Link Connector End View (C251)
G12751686Courtesy of FORD MOTOR CO.
Harness Side

Circuit Pin
CAN- (Controller Area Network) - VDB05 19 (WHITE)
CAN+ (Controller Area Network) - VDB04 20 (WHITE/BLUE)
Fig 2: PSCM-A Connector End View (C1463A)
G09694750Courtesy of FORD MOTOR CO.
Harness Side

Circuit Pin
Fig 3: PSCM-B Connector End View (C1463B)
G11676840Courtesy of FORD MOTOR CO.
Harness Side

Circuit Pin
CAN- (Controller Area Network) - VDB26 3 (GRAY/BLUE)
CAN+ (Controller Area Network) - VDB25 2 (GREEN/ORANGE)
  1. AP1: VERIFY PSCM DTC 
    • Ignition ON, engine OFF.
    • Clear the PSCM DTCs.
    • Ignition OFF.
    • Wait at least 90 seconds for the modules to completely shut off.
    • Ignition ON, engine running.
    • Carry out the PSCM self-test.
    • Is DTC U0159 currently present and active in the PSCM? 
      Yes No
      Go to  AP2. If the PSCM does NOT list DTC U0159 Lost Communication With The PAM, DISCONTINUE this test and REFER to the DTC Chart for diagnostic direction.
  2. AP2: INSPECT THE PSCM COMMUNICATION WIRING AND CONNECTORS 
    NOTE: The PSCM receives messages from other modules through 2 connectors: the PSCM-A (or B) 3-pin connector at the gear and the multi-pin in-line connector in the engine compartment. The in-line connector receives messages from there other modules into the PSCM wiring harness. The PSCM wiring harness uses the VDB wiring to carry the messages from the in-line connector to the PSCM-A (or B) 3-pin connector. If any of the connector pins or VDB communication wires are loose or damaged, the PSCM cannot properly receive messages from other modules.
    • Ignition OFF.
    • Disconnect PSCM-A (or B) 3-pin and the in-line electrical connectors.
    • Inspect both connectors for:
      • pushed-out pins, loose pins, spread terminals, water ingress and corrosion.
      • missing or loose latches, broken or cracked connector housings.
      • VDB wiring for pinched or cut wiring under brackets, air cleaner boxes, battery trays, engine pulleys, etc.
    • Inspect the VDB wiring for pinched or cut wiring under brackets, air cleaner boxes, battery trays, engine pulleys, etc.
    • Inspect the VDB wiring harness anchors for coming loose from anchoring locations in the engine compartment.
    • Repair the connectors or wiring as necessary.
    • Connect PSCM-A (or B) 3-pin and the in-line electrical connectors.
      • Verify connectors are solidly latched and connected without water ingress gaps.
      • Verify wiring harness anchors are solidly pushed into retaining holes, etc.
    • Ignition ON, engine OFF.
    • Clear the PSCM DTCs.
    • Ignition OFF.
    • Wait at least 90 seconds for the modules to completely shut off.
    • Ignition ON, engine running.
    • Carry out the PSCM self-test.
    • Is DTC U0100 present in the PSCM? 
      Yes No
      Go to  AP3. The concern is not present at this time and may have been set due to a loose or damaged electrical connector. The test is complete, no further action is required.
  3. AP3: CHECK THE HS-CAN CIRCUITS FOR AN OPEN 
    • Ignition OFF.
    • DLC connector disconnected. (C251)
    • PSCM_A connector disconnected. (C1463A)
    • PSCM_B connector disconnected. (C1463B)
    • Measure the resistance between:
      (+) PSCM_A (C1463A) Connector, Harness Side (-) DLC (C251) Connector, Harness Side
      CAN- CAN- - VDB05 - Pin 19
      CAN+ CAN+ - VDB04 - Pin 20
    • Measure the resistance between:
      (+) PSCM_B (C1463B) Connector, Harness Side DLC (C251) Connector, Harness Side
      (-)
      CAN- - VDB26 (GRAY/BLUE) - Pin 3 CAN- - VDB05 - Pin 19
      CAN+ - VDB25 (GREEN/ORANGE) - Pin 2 CAN+ - VDB04 - Pin 20
    • Are the resistances less than 3 ohms? 
      Yes No
      The HS-CAN circuits are OK, Go to  AP4. REPAIR the circuit.
  4. AP4: RECHECK FOR PSCM DTC U0159 
    • PSCM_A connector connected. (C1463A) Make sure the connector seats and latches correctly.
    • PSCM_B connector connected. (C1463B) Make sure the connector seats and latches correctly.
    • DLC connector connected. (C251) Make sure the connector seats and latches correctly.
    • Ignition ON, engine OFF.
    • Clear the PSCM DTCs.
    • Ignition OFF.
    • Wait at least 90 seconds for the modules to completely shut off.
    • Ignition ON, engine running.
    • Carry out the PSCM self-test.
    • Is DTC U0159 currently present and active in the PSCM? 
      Yes No
      The PSCM is not the cause of the concern.
      RETRIEVE and RECORD all PAM DTCs. REFER to Diagnosis and Testing in the appropriate Parking aid article and DIAGNOSE the PAM.      		 If the PSCM no longer lists DTC U0159, the concern was repaired during this pinpoint test and the PSCM HS-CAN circuits are working correctly at this time.
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